Embodiments disclosed herein relate to the field of database technology, and, more specifically, to a method and system for importing E-R model data utilizing dependency information in an E-R model data schema.
Entity-Relationship data model (E-R) model is a semantic model, which is very useful in the mapping from meanings of the real world to conceptual patterns. The E-R model involves three basic concepts: an entity set, a relationship set, and properties.
Generally speaking, there are three possible scenarios for the correlations between entities in the E-R model data. The first scenario is a strong correlation, which means that a certain entity type is linked to N (N≧1) instances of another certain entity type. In other words, a certain entity has a property that is another entity type, whose number of the property being at least 1. For example, the entity “student” has a property “name,” while “name” itself is also an entity, which further comprises properties such as “surname,” “first name,” “former name,” etc. Since every student must have at least one name, the entity type “student” is strongly correlated to the entity type “name.” The second scenario is a weak correlation, which means that a certain entity type is linked to N (N>=0) instances of another certain entity type. For example, the entity type “student” has a property “duty,” while the “duty” itself is also an entity type having a plurality of properties (for example “start time,” “tenure”). Since not every student takes a certain duty, the entity type “student” is weakly correlated to the entity type “duty.” The third scenario is no correlation. In other words, no correlation means no correlation exists between two entity types.